Theoretical computation of the electrical conductivity of thermal plasmas-application to plasma torch design of an electrothermal launcher

Designing a plasma torch that allows the ignition of gun propellant is generally complex. In this paper, however, we show that it is possible to design a torch from using simplified calculation of electrical conductivity with the help of an experienced design method (Doehlert matrix). First, we explain how to obtain plasma composition both at and out of thermal equilibrium. Then, we compare the simplified calculation with the complete calculation of electrical conductivity. Then, we construct a Doehlert matrix as a function of temperature and thermal nonequilibrium. Finally, we study the length/diameter ratio versus the length and resistivity